The Gulf of California (GOC) hosts one of the most oblique rifts on Earth, where dextral shearing exceeds extension by a factor of ~3 and presently accommodates ~90% of Pacific–North America transtensional deformation. Understanding the processes that governed GOC opening requires constraints on the rates and directions of rifting through time. Since ridge–trench interactions began at ~16 Ma, plate-margin deformation has been partitioned into two belts of weak lithosphere: (1) the former accretionary prism west of the Baja California microplate and (2) the GOC, which contains the Miocene arc axis and likely overlies a slab window. Despite decades of study, no consensus exists regarding the direction or rate of GOC opening during the earliest phase of rifting. Kinematic studies of the oldest rift-margin faults document predominantly margin-normal extension, leading some workers to infer that the dextral component of plate motion was initially accommodated in the accretionary wedge. However, this interpretation is not unique. Strain gradients and kinematic partitioning within the GOC can focus lateral shearing into the rift axis, where it is difficult to recognize, while leaving extensional strain dominant along the margins. Seismic reflection data and high-resolution multibeam bathymetry show that accommodation zones linking the earliest extensional fault systems are consistently oriented NW, indicating that dextral shearing dominated GOC deformation from the onset of ridge–trench juxtaposition at ~16 Ma. Restoration of the Magdalena Fan to its likely source area in Baja California constrains dextral shearing within the accretionary prism to <150 km, requiring at least ~450 km of dextral displacement within the GOC since ~12.5 Ma. These relationships imply a progressive transfer of strain from the accretionary wedge into the GOC. All major faults west of Baja California control deep rift basins, indicating that regional slip transfer did not significantly alter the ratio of dextral shearing to extension within the GOC. Revised plate-circuit models further indicate that the direction of relative plate motion has changed little since ~16 Ma. Consequently, opening models that invoke a late increase in dextral shearing to explain inundation pathways or rapid continental rupture require reevaluation. The evolution of the GOC is more consistently explained by sustained oblique rifting aligned with relative plate motion, accompanied by a progressive increase in strain rate since ~16 Ma.